7/23/2001 @ 12:00AM

The Next Small Thing

Scientists are re-creating our world in the realm of the intensely tiny. The potential payoff: denser hard drives, smaller chips, better medicine.

Science is venturing into a new borderland, one as mysterious as the deepest oceans and as foreign as intergalactic space. It is the realm of the tiny, where things are measured in an unimaginably small unit called a nanometer, a distance one-hundred-thousandth the width of human hair. In this place the distinctions we learned in high school between “squishy” biology and “hard” physics melt away. In nanotechnology everything is simply atoms. The scientist-explorers in this space are learning how to move those atoms and coax some to work with others, all in an attempt to change the very nature of matter itself.

Function follows form: Change the molecular structure of the materials used to make computer chips, for instance, and electronics could become as cheap and plentiful as bar codes on packaging. Lightweight vests enmeshed with sensors could measure a person’s vital signs. Analysis of a patient’s DNA could be done so quickly and precisely that designer drugs could be fabricated on the fly. A computer the size of your library card could store everything you ever saw or said.

In this fourth annual spotlight on innovators, FORBES has turned to the scientists laying the groundwork for this custom-made future. Nanotechnology is still in its early days. Our six pioneers are kindred spirits to those who produced crude solid-state electronics after the invention of the transistor or who roughed out the Internet in the early 1970s. “We’re working out the rules of biology in a realm where nature hasn’t had the opportunity to work,” says Angela Belcher, a professor with the University of Texas.

Much of the work is aimed at building future electronic systems, whose manufacturing limits are becoming clear. Using established technology, such as lithography, the best that chip manufacturers can currently do is make circuit elements with dimensions measuring 130 nanometers across. The prospect of building electronic systems that could be 1,000 times denser and significantly cheaper, bit for bit, is alluring. Redirecting chipmaking techniques for biology could dramatically improve how doctors diagnose and treat the ill.

None of this is easy, in no small part because scientists will be freely trespassing on one another’s turf. To make such tiny electronic circuits, physicists are trying to mimic nature by finding ways to get inanimate materials to “self-assemble,” in a fashion analogous to the way living things grow.

There are risks. Some nanotechnology tricks being investigated now will never be commercially feasible, and even the ones that will be could also attract the same sorts of hucksters that flocked to the Internet. Pundits even debate the possible unintended consequences of nanosystems, including whether nanomachines could spiral out of control.

The scientists profiled below hail from some of the world’s top research organizations within both large companies and renowned universities. Their entrepreneurial spirit has pushed some to branch out to startups that aim to commercialize their work. The future will indeed be amazing. Watch these scientists make it so.

Gerd Binnig, a fellow at IBM, remembers when other scientists would visit his laboratory in Zurich and angrily denounce him and colleague Heinrich Rohrer, as cheaters. “They just didn’t believe us,” he recalls. In 1981 Binnig and Rohrer built what they called a “scanning tunneling microscope.” Painting snapshots of the surface of inorganic material, such as metal or semiconductors, the STM gave scientists their first visa to the nanoworld.

By bringing a metal probe within two atoms of a sample material, Binnig and Rohrer showed that the material’s surface was as bumpy as the Rocky Mountains instead of smooth and uniform, as most previous calculations had assumed. Even Binnig could hardly believe their results. “I thought matter was simpler. I was impressed by its beauty.”

As soon as scientists could see individual atoms, they wanted to start playing with them. (The work also won Binnig and Rohrer a share of a Nobel Prize in 1986.) Fast-forward to the present: Rohrer, 68, is retired, but Binnig, 54, is breaking new nanoground–literally–with his “millipede” storage system that can record more than 400 gigabits of data over a square inch. That’s a 50-fold step up from IBM’s densest commercial drive, a 70-millimeter platter that packs 26 gigabits.

Along with a team of IBM colleagues in Zurich, Binnig created a nanoscopic brush with 1,024 tiny tips, each attached to its own cantilever. As the cantilevers move up and down, they make dents in a plexiglass-like polymer; picture an inverted version of the bumps on a roll of music for a player piano designed to charm an amoeba. The tips can also “read” the dents back, at rates of up to 100 megabits per second, by brushing back over them. To start over again, heat the polymer and the dents disappear as the molecules realign themselves. “Our intention was to demonstrate that nanotechnology isn’t that far out,” declares Binnig.

It will take IBM two to three years to commercialize the millipede storage system, Binnig expects. That the millipede works at all surprised even Binnig, who says he procrastinated building the device because he thought it wouldn’t work. In the nanorealm “your intuition fools you,” Binnig says. “You might think it would not work–but it does.”

At the heart of Binnig’s work are mechanical principles. Others are turning toward nature for insights into how to manipulate matter. Nature builds nanostructures all the time. But rather than painstakingly trying to assemble every feature, biological systems essentially are programmed with rules that guide how materials should build themselves.

Chemists work much the same way, says George M. Whitesides, 62, who joined Harvard University as a tenured chemist in 1982. “Chemists have always been in the business of taking atoms and putting them together with other atoms with precisely defined connections,” he says.

That kind of work used to be aimed at concocting new drugs. Now it’s aimed at the microchip business. By the 1980s microelectronics engineers were beginning to worry that packing ever more transistors onto computer chips was going to get impossibly expensive. Whitesides, who had long served as a consultant to the Department of Defense, had a reputation for doing unconventional chemistry by exploring interactions between unlikely pairings of materials. Why not, he asked, put chemistry to work to make novel electronic circuits?

That question has led Whitesides to the forefront of one of the most intriguing nano-explorations: figuring out how to coax materials to “self-assemble,” or put themselves together in precise ways.

Trying to build nanoscale electronics with even the most sophisticated tools from the chip business is exquisitely hard–like doing a tiny line drawing with an infant’s extra-thick crayons. By contrast, living cells are full of machinery that assemble nanoscale structures all the time.

Inspired by the complex structure of proteins, Whitesides thinks he can build a three-dimensional circuit that assembles itself. He takes tiny polymer blocks and affixes electronic devices like transistors on a number of faces. His team adds solder dots on other faces, then strings the blocks together like beads on a fine wire.

The “magic” is in the solder dots, which are attracted to one another, much the way two drops of water on a windshield merge into one. The die sides with, say, two solder dots are attracted to others with two solder dots; those with three are attracted to other groups of three.

Suspend the necklaces of blocks in water and the solder dots come together, forming connections and, ultimately, a three-dimensional circuit. “If we do the design right, this thing should fold together just one way,” Whitesides says.

Making, say, 500 components come together is daunting, he adds. “But we’re not steering blind. Nature does it. We know that 500 amino acids can fold to make just one protein.”

Angela Belcher, 34, of the University of Texas, also believes that proteins are the keys to unlocking new semiconductor materials. Abalone, she says, make their shells by creating a fine brick-like wall of nanosize tiles of two types of chalk, something that makes them 3,000 times tougher than the chalk found in rock. “They’re perfect nanostructures, and that’s related to why they’re so tough,” she says. Proteins signal when the abalone should grow a tile. As Belcher was finishing her graduate degree, she made a conceptual leap: Why not use proteins to direct the nanostructure of semiconductors? “People didn’t think about putting these things together,” Belcher says. “Most just thought, “This will never work.’”

Structure matters. For decades, silicon engineers have worked hard to make silicon crystals grow as perfectly as possible so that electrons will whiz through, producing a faster chip. Belcher wants to control far more aspects of crystal growth. She did not know which proteins might trigger semiconductor growth. So she turned to a time-tested approach from the pharmaceutical industry: Throw the kitchen sink at ‘em.

She started with a billion viruses, each carrying a different genetically modified protein. She mixed them in solution with a semiconductor, then checked to see whether some proteins would stick to the semiconductor. The technique worked. She washed away the irrelevant ones, then repeated the process. By running through the routine a half dozen times, Belcher began to believe that she could control how semiconductor crystals grow.

Now, two years later, Belcher and her team are collecting a toolbox of proteins that alter crystal growth in various ways. “It took the abalone millions of years to evolve,” Belcher says, to get the right proteins. “It takes about three weeks on the bench top.”

Working through the periodic table, Belcher’s university team has tested proteins that stick to about 20 different inorganic materials. This spring Belcher and Evelyn Hu of the University of California, Santa Barbara, cofounded a company, Semzyme, to systematically develop a protein toolkit. “Right now, we’re trying to learn the rules,” she says.

Harold Craighead, 48, recently appointed dean of engineering at Cornell University, is trying hard to break the rules–at least, the traditional rules that separate fields like physics and biology. At Cornell’s Nanobiotechnology Center physicists, engineers, biologists and chemists collaborate, crushing the time-honored academic distinctions separating them. He tries to do the same in his own work as a scientist, using a physicist’s collection of tricks to understand and work with biological molecules. He pokes, prods and stretches DNA molecules to understand the physics that govern them. One result: a technique for dramatically speeding up the job of separating large fragments of DNA, a likely boon for diagnosing diseases.

To study the properties of DNA molecules, Craighead and his associates employ lithographic equipment like that used by the chip industry to make tiny obstacle courses for molecules. On a piece of silicon, they etch tiny channels with bumps 35 to 90 nanometers high. They then put a drop of solution containing DNA fragments at one end of the channel and turn on an electric field: weirdly enough, the bigger the fragments, the faster they move over the bumps. It takes only a few minutes for Craighead’s group to separate large DNA fragments from a sample. Traditional means could take many hours for the same material.

Marrying molecular biology and lithography is already producing a wealth of other novel diagnostic techniques. One of Craighead’s favorites: a tool that could detect whether food is spoiled. It’s the micron equivalent of a dipstick, a tiny cantilever with antibodies on the tip. The antibodies attach to certain bacteria, causing the cantilevers to vibrate. Electronic systems sense the vibrations and set off an alert. With such nanoscopic feelers, they can detect even a molecule of gas.

“This is no more sophisticated than the electronics in a singing birthday card,” Craighead says. Such systems could easily be built into every refrigerator.

R. Stanley Williams, 49, and a fellow at Hewlett-Packard, just wants to build a better computer. “A computer still isn’t smart and isn’t easy to use,” Williams says. “We want to make vastly more capable computers that are cheaper to build and that run on less power.”

The model Williams and his colleagues have in mind is, of course, the human brain, an instrument with trillions of neurons. Any one neuron is slower to act than a transistor on a Pentium chip, but collectively, the brain’s neurons process far more information than the biggest array of Pentiums.

To mimic the brain Williams needs switches and wires thousands of times smaller than those in the best silicon devices and a radically different design for the overall computer. For switches Williams and his HP colleagues, along with James Heath at the University of California, Los Angeles, are turning to molecules. Carbon nanotubes are promising candidates for wires. They are atomically perfect structures, 1 to 2 nanometers wide, and as much as a million times as long. Some are metallic and have proven to be the best conductors yet discovered, others are semiconductors.

For their system Williams and his colleagues construct an electronic sandwich: a layer of wires, then a layer of rotaxane molecules that act like switches, topped with another layer of wires that run perpendicular to the first layer. The molecules become devices at the points where the wires cross.

Some of the molecular switches may not work–something that would be a devastating problem for conventional electronic circuits. But the scientists believe they can livewith defective components by programming their way around them, a trick that has been used in some kinds of silicon chips and in experimental computers.

That’s the future. For now Williams and his team are tackling such fundamental challenges as showing that their switches work and figuring out how to get data in and out of tiny molecular devices.

At UCLA Heath is nearing the end of a two-year effort to build a molecular 16-bit memory unit. “By the end of summer we’d like to demonstrate, on a nanometer scale, logic devices that are like the chips you could buy in 1970,” Williams says. “Then we’d like to boost performance eight times every 18 months,” he adds, in order to achieve a 16-kilobit memory by 2005. If he is successful, he reckons that in ten years his devices will rival the power of the best available conventional silicon chips. Yet because his chips will be built from organic molecules, manufacturing them might be more like rolling out a sheet of photographic film than etching squares of silicon, Williams says.

Mark Reed, 46, now chairman of Yale University’s electrical engineering department, is convinced that some form of electronics will ultimately be built from self-assembling components. In the beakers in his laboratory he is exploring just what types of molecules can be coaxed to work together to conduct current.

In June Reed published a paper describing how he made memory devices by sandwiching carbon-based molecules between two dots of gold measuring less than 50 nanometers across. Apply a voltage to the device and the molecules rearrange themselves to conduct, essentially turning on. Other pulses can nudge the molecules to rearrange themselves into a nonconducting state, turning off much as a random access memory chip does. Still other voltage pulses can read whether the molecules are off or on.

“Our next step is to get our hands on the knobs of the controls,” says Reed, by understanding the physics behind how electrons move through such materials. “Molecular devices could be used to replace memory. Will they be as good as silicon? Probably not. Will they be cheaper? Yeah.”

Imagine, he says, memory so cheap that people throw away electronics the way they do packaging. When electronics are that cheap, the way we use them changes fundamentally. Electronics, for instance, could replace bar codes. Shoppers would still pick groceries off the shelf, but rather than waiting in a checkout line, they would wheel their loaded carts through a portal like a metal detector. The electronics would signal how much should be deducted from the shopper’s bank account.

Nice–yet Reed contends that the most intriguing applications have yet to be invented. “If you had extrapolated from 1950s technology, we’d all have nuclear-powered toasters instead of PCs on our desks.”